Firkin Around....
The Blog of King of Prussia Beer Outlet

Wednesday, March 25, 2015

Oh the Difference a Yeast Makes

by Matt DeMarco

One amazing thing about beer is that despite the multitude of brands and styles there are only 2 classifications of beer--lagers and ales.  For example, a pilsner is part of the lager family and IPAs are part of the ale family. These classifications are based on the type of yeast used in fermentation. Prior to fermentation, malt is cracked to release the starch within the grain and then mixed with water.  The mixture or wort is then heated to convert the starch into sugars.  Fermentation begins when yeast is added to the wort.  During fermentation, the yeast feeds on the sugar excreting alcohol and C02.  Top fermenting or ale yeast stays on top of the wort while it is active and then sinks to the bottom when all of the fermentable sugar is consumed. Bottom fermenting yeast or lager yeast is the opposite and stays on the bottom of the wort the whole time.